The participating laboratories share a common interest in understanding Drosophila development and its relevance to human development. Individual research areas include the role of homeotic genes in developmental programming, hormonal regulation of gene expression and cell proliferation, and the development and function of various parts of the nervous and chemosensory systems. The goals are to elucidate the genetic and molecular bases of these complex processes. Since the degenerative phenomena associated with aging are evident in Drosophila, and appear to involve changes of cell differentiation and function, we propose to extend our research, individually and collaboratively, to include a developmental approach to aging in Drosophila. All of the proposed experiments are based on the use of mutants to dissect complex developmental processes, so that the relevant genes can be identified and cloned and their roles in development and aging studied in molecular detail. Since many basic mechanisms of development have been conserved to a significant extent during evolution, information obtained about Drosophila, which offers so many advantages for molecular genetics, is likely to be relevant to related phenomena in other organisms including humans.